I need help on a question real quick

If 3x+8=3x+8 is it one solution or no solution

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

What is the value of x? enter your answer in the box.